How can I create intercalated shapes?
Start with a plane. Keep it as separate object and add a &quot;solidify&quot; modifier and some subdivision.

Now in side view, in edge selection mode, select the top edge and extrude it along:

Keep the modifiers as long as possible in order to manage the fiewer vertices manually.
Do it for side parts too, and join the parts at the top, and adjust the heights as needed:

Once happy with the shape, apply &quot;solidify&quot; modifier, select the edges and bevel them:

You should obtain something like this: